AROUND 2.7 million families — equivalent to the population of Manchester, where the Tories are gathering for their annual conference this weekend — could be £3,000 worse off after swingeing tax credit cuts.

Low and middle-income workers and their 5.2 million dependent children will feel “significant” strain on their finances when the cuts come into effect next April, research by public-sector union Unison found.

But while Tories pat each other on the backs during the conference in central Manchester, tens of thousands of people will take to the streets in a protest organised by the TUC and People’s Assembly against the party’s damaging “austerity” ideology.

A colossal 357,000 families in London — the highest number in Britain — will be hit by the axing of working and child tax credits, which subsidise bosses who do not pay a living wage.

Almost 270,000 households in the West Midlands will be in the red by up to £3,000 a year and at high risk of taking on costly debts just to make ends meet, according to Unison.

A quarter of a million families in Yorkshire and the Humber are to learn in December that they will be hit by Chancellor George Osborne (pictured) seizing £4.4 billion a year from tax credit coffers.

In Wales, 135,000 families will be affected by the changes — while higher-earners and corporations across Britain get away with enjoying more generous tax breaks.

Unison general secretary Dave Prentis said: “Many of the millions of families who will be the victims of the Chancellor’s cruel tax credits snatch-and-grab still have no idea that they are going to lose out next year.

“When they start receiving letters in the post from HMRC just before Christmas, it will mean chaos for family finances.”

This pours cold water on the Tories’ manifesto claim to be the “party of working families,” said Labour.

Shadow minister without portfolio Jonathan Ashworth said: “It’s clear that couldn’t be further from the truth. The Tories’ choices since the election will hit working people hard.”

More than a quarter of voters (27 per cent) said they would be put off voting for the Conservatives because of the raid on lower-income families, a Huffington Post poll revealed.

The highest level of discontent was found among skilled manual workers, with 31 per cent of those surveyed saying tax credit cuts made them less likely to back the Tories in 2020.

“Only Labour will stand up for working families struggling to succeed in an economy that doesn’t work for them,” Mr Ashworth added.

Unison urged the Chancellor to reconsider his position before more irreparable damage was done.

Mr Prentis said: “It’s time for the Chancellor to admit that he’s got this one very wrong and back down before it’s too late.”

The Tories should be “ashamed of themselves,” said shadow chief secretary to the Treasury Seema Malhotra.

She added: “Over the next weeks and months, Labour will be taking its campaign to stop the tax credit cuts to high streets and homes across Britain.”